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Vitamin D target proteins: function and regulation

S Christakos1, F Barletta, M Huening

  • 1Department of Biochemistry, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA. christak@umdnj.edu

Journal of Cellular Biochemistry
|January 10, 2003
PubMed

Insights

Calbindin-D(28k) protects cells from degeneration, including osteoblasts and pancreatic beta cells. CCAAT enhancer binding protein beta (C/EBPbeta) is a new vitamin D target gene involved in regulating 24-hydroxylase transcription.

Area of Science:

  • Cell Biology
  • Endocrinology
  • Molecular Biology

Background:

  • Calbindin-D(28k), a vitamin D target, protects osteoblasts and pancreatic beta cells from apoptosis and degeneration.
  • 1,25(OH)(2)D(3) also induces 25(OH)D(3) 24-hydroxylase (24(OH)ase), crucial for vitamin D catabolism.

Purpose of the Study:

  • To investigate the role of CCAAT enhancer binding protein beta (C/EBPbeta) as a novel vitamin D target gene.
  • To determine C/EBPbeta's function in regulating 24(OH)ase transcription.

Main Methods:

  • Investigated calbindin-D(28k) expression and function in osteoblasts and pancreatic beta cells.
  • Analyzed the induction of C/EBPbeta by 1,25(OH)(2)D(3) in kidney and osteoblastic cells.
  • Assessed the effect of C/EBPbeta on 24(OH)ase transcription.

Main Results:

  • Calbindin-D(28k) demonstrates a protective role against cellular degeneration beyond calcium transport.
  • C/EBPbeta is identified as a novel 1,25(OH)(2)D(3) target gene.
  • C/EBPbeta enhances the transcriptional activity of 24(OH)ase in response to 1,25(OH)(2)D(3).

Conclusions:

  • Calbindin-D(28k) plays a significant role in cellular protection against degeneration.
  • C/EBPbeta is a key regulator in the vitamin D signaling pathway, influencing 24(OH)ase expression.
  • These findings expand the understanding of vitamin D receptor-mediated gene transcription and cofactor recruitment.

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